I was unable to find this tip already here on vvv.org, it should probably be in the wiki somewhere.
Since the explorer search function in Win7 (and later?) uses the tilde (~) as a wildcard, in order to find vvvv patch backup files you need to use this:
If you use just *~.xml, you will actually match ALL .xml files, not a good thing if you are trying to do some housecleaning.
I’ve found that packs and other contributions have quite a few ~.xml files in them, so here is an easy way to remove the cruft.
I had 1661 ~.xml files in my work folders! Yeesh, no idea I’ve edited that many files, they do add up!